This invention relates generally to improvements in turbine blades such as a stator vane or rotor blade in a gas turbine engine. More specifically, this invention relates to an improved turbine blade of the internally cooled type, wherein the turbine blade is formed to define a heat transfer surface designed for improved heat transfer with a cooling gas stream.
Internally cooled turbine blades in a gas turbine engine are generally known in the art. Such turbine blades, including fixed stator vanes and moving rotor blades, are formed to include an internal flow path for flow-through passage of a cooling gas stream to prevent overheating of blade surfaces. In a typical design, the cooling gas stream comprises a compressed air bleed flow from an engine compressor or compressor stage. In this regard, it is desirable to minimize the cooling flow requirements for regulating blade temperature, so that a maximum compressor discharge flow is available for supply to the engine combustor resulting in maximized overall engine efficiency.
In the past, internally cooled turbine vanes have been designed with a variety of different surface geometries intended to improve heat transfer between the turbine blade and the cooling gas stream, in efforts to reduce blade cooling flow requirements. In some of these designs, improved heat transfer has been achieved with specific surface geometries for increasing the turbulence of the cooling gas stream as it passes through the internal blade flow path.
There exists, however, a significant need for further improvements in internally cooled turbine blades, particularly with respect to increasing heat transfer between the blade and a cooling gas stream. The present invention provides an improved heat transfer surface on the blade for achieving this objective.